LeetCode刷题实战588：设计内存文件系统
ls: Given a path in string format. If it is a file path, return a list that only contains this file's name. If it is a directory path, return the list of file and directory names in this directory. Your output (file and directory names together) should in lexicographic order.mkdir: Given a directory path that does not exist, you should make a new directory according to the path. If the middle directories in the path don't exist either, you should create them as well. This function has void return type.addContentToFile: Given a file path and file content in string format. If the file doesn't exist, you need to create that file containing given content. If the file already exists, you need to append given content to original content. This function has void return type.readContentFromFile: Given a file path, return its content in string format.示例
输入:
["FileSystem","ls","mkdir","addContentToFile","ls","readContentFromFile"]
[[],["/"],["/a/b/c"],["/a/b/c/d","hello"],["/"],["/a/b/c/d"]]
输出:
[null,[],null,null,["a"],"hello"]
解题
class FileSystem {
public:
FileSystem() {
dirs["/"];
}
vector<string> ls(string path) {
if (files.count(path)) {
int idx = path.find_last_of('/');
return {path.substr(idx + 1)};
}
auto t = dirs[path];
return vector<string>(t.begin(), t.end());
}
void mkdir(string path) {
istringstream is(path);
string t = "", dir = "";
while (getline(is, t, '/')) {
if (t.empty()) continue;
if (dir.empty()) dir += "/";
dirs[dir].insert(t);
if (dir.size() > 1) dir += "/";
dir += t;
}
}
void addContentToFile(string filePath, string content) {
int idx = filePath.find_last_of('/');
string dir = filePath.substr(0, idx);
string file = filePath.substr(idx + 1);
if (dir.empty()) dir = "/";
if (!dirs.count(dir)) mkdir(dir);
dirs[dir].insert(file);
files[filePath].append(content);
}
string readContentFromFile(string filePath) {
return files[filePath];
}
private:
unordered_map<string, set<string>> dirs;
unordered_map<string, string> files;
};